The funky, quacky, vowel-like effects of a perfectly set envelope filter pedal can really get us grooving. This “auto-wah” filtering effect is easily identified in music and is well-worth the investment when used tastefully.
If you’re looking for the best envelope filter pedals money can buy, you’ve come to the right place. Of course, any “best of” list is a highly-subjective matter.
That being said, I believe I’ve nailed down the best envelope filters on this list. I would completely expect another person’s list to be different (but hopefully it would overlap)!
The top 13 best envelope filters pedals for guitar and bass are:
- Electro-Harmonix Q-Tron + (+ Micro Q-Tron)
- EarthQuaker Devices Spatial Delivery
- Mojo Hand Wonder Filter
- Maxon AF-9
- Pigtronix Envelope Phaser
- Source Audio SA127
- DOD 440
- Source Audio SA143
- MXR M82 Bass Envelope Filter
- Electro-Harmonix Bassballs
- Mr. Black Fwonkbeta Purple Funk Generator
- Xotic Robotalk 2
- Mu-Tron Micro-Tron IV
Let’s discuss each pedal on this list and the reasons why they are the best.
What Are Envelope Filter Pedals & How Do They Work?
Envelope filter pedals produce various envelope-triggered filtering effects in the audio signal.
Envelope filtering is the filtering triggered by the envelope or transients of a signal. These filters act according to the attack and decay of the notes (or chords) of the guitar. Hit a note and the filter will trigger and follow the amplitude of the note.
The sound of an envelope filter is often described as wah-like or like a duck’s quack. There are various filter types (high-pass, band-pass or low-pass) that can be triggered when a guitar or bass note is struck.
An envelope filter will then sweep the peak response of a frequency filter up or down, creating a spectral glide similar to the wah effect. The biggest difference is that it’s the dynamics or the input signal that triggers the frequency modulation/filtering rather than an expression pedal.
Envelope filter pedals, like wah pedals, often benefit the tone of a guitar when placed near the front of the signal chain
Related article: How To Order Guitar/Bass Pedals (Ultimate Signal Flow Guide)
With that being said, let’s talk about some envelope filter pedals!
For a more in-depth article on envelope filter pedals, check out my article What Are Envelope Filter Effects Pedals & How Do They Work?
Electro-Harmonix Q-Tron +
First on this list is the well-known and well-respected Electro-Harmonix Q-Tron+ (link to check the price on Amazon) envelope filter pedal.
The Q-Tron+ from EHX is basically the same design as the original Q-Tron (now discontinued) with the addition of an effects loop and an attack response switch. It’s a very powerful and versatile pedal for musical expression.
This envelope filter has 4 distinct modes (filters) of operation:
- Low-pass (LP)
- Band-pass (BP)
- High-pass (HP)
- Mix: a combination of the BP mode with the direct signal
The Q-Tron+ also has a boost mode. When boost mode is off, the gain knob acts simply as a sensitivity control for the envelope filter circuit. When boost mode is engaged, the gain knob doubles as a sensitivity and output gain control.
With each filter mode, we have 4 distinct parameter controls:
- Response: changes the sweep response between fast and slow settings. This controls how fast the envelope will sweep the filter.
- Range: in low position, the pedal emphasizes vowel-like sounds and in high position, the pedal emphasizes overtones.
- Peak: controls the resonance peak or Q of the filter.
- Sweep: toggles between an upward filter sweep and a downward filter sweep.
These features alone make the Q-Tron+ a fully functional envelope filter. Its versatile and nearly perfect performance makes it one of the best envelope filters out there. But there’s more!
The EHX Q-Tron+ has an effects loop. We can effectively place an additional effect, or chain of effects between the Q-Tron Plus’s preamp and filter section without changing the envelope drive.
This opens up a world of new possibilities with the Q-Tron+. Try placing a fuzz pedal in the loop to help shape the typically uncontrollable sound of fuzz. Get creative and try out pitch-shifting or other filter pedals (inserting another Q-Tron+ into the loop can yield wicked results).
What we get with this true bypass pedal is a flexible and durable envelope filter that sounds great and delivers awesome effects time and time again.
The Micro Q-Tron (link to check the price on Amazon) is another superb envelope filter from EHX. It is essentially the original Q-Tron with a small footprint and fewer features.
Electro-Harmonix is featured in My New Microphone’s Top 11 Best Guitar/Bass Effects Pedal Brands To Know & Use.
EarthQuaker Devices Spatial Delivery
Second up is the sweet and simple EarthQuaker Devices Spatial Delivery (link to check the price on Amazon).
If we were to pick up any random EQD pedal, chances are it would be weird. The Spatial Delivery in no exception.
This pedal is a voltage-controlled envelope pedal that includes a sample and hold circuit.
The Spatial Delivery has 3 modes, selectable via the 3-way toggle switch:
- Up Sweep: the filter sweeps upward in reference to the input signal level/envelope.
- Down Sweep: the filter sweeps downward in reference to the input signal level/envelope.
- Sample and Hold: filter is controlled by random voltage.
So we can 2 typical envelope filter modes and 1 that sounds totally weird and uncontrollable.
Of course, there are controls to help us shape all 3 modes. They are:
- Range: adjusts the sensitivity of the envelope in Up Sweep and Down Sweep modes. controls the sweeping speed in Sample and Hold mode.
- Resonance: adjusts the filter feedback control, adding or subtracting body and ring in the filter voice.
- Filter: crossfades between high-pass (fully counterclockwise) and low-pass filters (fully clockwise), with continuous versions of a band-pass filter in the middle.
The Spatial Delivery features EarthQuaker Devices’ Flexi-Switch technology: a relay-based, true bypass switching system that allows both momentary and latching switching simultaneously.
Latching is accomplished by tapping the footswitch and momentary operation is accomplished by holding the footswitch down.
From classic funky envelope filter effects to “deep fried space droid computer freak-outs”, the EQD Spatial Delivery has you covered!
EarthQuaker Devices is featured in My New Microphone’s Top 11 Best Guitar/Bass Effects Pedal Brands To Know & Use.
Mojo Hand Wonder Filter
A best envelope filter really wouldn’t be complete without the Mojo Hand Wonder Filter (link to check the price on Amazon).
The Wonder Filter is inspired by the classics. It’s an awesome-sounding true bypass pedal with everything we’d want from an envelope filter.
Let’s begin by defining the Mojo Hand pedal’s 5 modes, selectable via the bottom-most dial:
- No Filter (0): setting offering preamp stand-alone boost capability.
- High Pass Filter (HP)
- Band Pass Filter (BP)
- Low Pass Filter (LP)
- Notch Filter (N)
We understand, by the No Filter mode description, that the Wonder Filter has a boost circuit. The amount of boost will effect all modes equally in terms of an increase in output gain.
The gain control knob will feed more input signal into the envelope and, thereby, increase the sensitivity of the envelope filter circuit.
The Mix knob brings in some amount of the direct signal to blend the dry and wet signals together.
The attack and resonance peak amplitude can also be controlled via knobs.
This pedal has toggle switches for Range (low and high) and Drive (down and up). The low range setting emphasizes vocal-like sweeping while the high range produces sweeping in the harmonics.
All in all, this is a very neat and multifaceted envelope pedal. It can be set up to sound just how you like it and its high-quality audio gives it a step up on its competition.
The Maxon AF-9 (link to check the price on Amazon) is an outstanding and simple envelope filter.
The Maxon AF-9 is based on the beloved design of the vintage Mu-Tron III (we talk about the Mu-Tron Micro-Tron IV later in this article).
This pedal has undergone a few changes but still gives us that wet, funky, vowel-like auto-wah sound we enjoy so much from top-of-the-line envelope filters like the venerable Mu-Tron III.
The AF-9 is built with durability and simplicity in mind. It’s got a large footswitch pad; 2 knobs and 3 switches.
The pedal sounds incredible. Let’s dive a bit deeper into its functionality.
Maxon’s AF-9 has the 3 standard filter types: low-pass, band-pass and high-pass. These types are selected via one of the toggle switches.
The other 2 toggle switched control the direction/drive of the filter sweep (up or down) and the range of the sweep (high or low).
The 2 knobs control the circuit’s sensitivity to the input signal and the peak amplitude of the filters’ resonance frequencies.
Opto-coupler circuitry produces the shimmering, watery filtering of legendary vintage units. So we have a classic-sounding envelope pedal with all the go-to controls. This makes the Maxon AF-9 one of the best envelope filter pedals on the market.
Pigtronix Envelope Phaser
The Pigtronix Envelope Phaser (link to check the price at Pigtronix) is a bit of a step beyond a standard envelope filter in its phaser functionality but its envelope filtering sound is superb.
Really, this pedal is a phaser with additional envelope controllability. However, I want to add this pedal to list as a special inclusion.
The phase-shifting circuit can be controlled via the typical LFO modulator or by the envelope of the input signal. We can even blend these controls together to get a more creative and novel sweeping effect.
With the Envelope Phaser, we can switch between the swirl of a uni-vibe and the quack of a Mu-Tron with a single footswitch stomp.
This Pigtronix pedal has 2 expression pedal inserts to control the speed and sweep of the phaser along with controlling the continuous blend between envelope and LFO modulation.
It also has a separate envelope filter trigger insert, allowing a separate audio source to control the envelope circuit rather than the input signal.
The pedal sounds great as a phaser. It has the typical depth, centre, speed and resonance controls to alter the effect.
The secondary footswitch selects between the envelope filter (EF) and LFO modulation of the phaser. The two modulators can be blended together via the Blend toggle switch.
Let’s talk about how it works as an envelope filter.
Like a typical envelope filter, the envelope is produced according to the input signal. This is the case unless an external source is plugged into the 1/4-inch EF Trigger port.
The sensitivity of the envelope filter can be adjusted via the Sensitivity knob and the direction of the filter sweep can be toggled between upward and downward motion.
The Staccato switch alters the speed of the envelope. In on position, an “intelligent envelope” listens to the playing and quickly discharges the envelope between notes.
What we have, then, is an incredible two-in-one pedal that can act as a phaser; an envelope-controlled phaser or as a standard envelope filter. Not only is the Pigtronix Envelope Phaser capable of doing all these things but it excels in all of them, making it a superb choice as an envelope filter pedal.
Source Audio SA127
The Source Audio SA127 (link to check the price on Amazon) is one of the pedals from Source Audio’s incredible Soundblox line. Unfortunately, this pedal has been discontinued.
The SA127 features a whopping 21 filter types and a variety of control options. This powerful unit is capable of producing a wide range of envelope filter effects from traditional auto-wah to advanced and even novel sounds.
The 21 modes that make this pedal so awesome are categorized in 6 categories (2-pole filters; 4-pole filters; single peak; triple peaks; peak and notches, and phasers). They are:
- 2-Pole Filters
- 1: Resonant Low-Pass: A flat response at low frequencies, rising to a resonant peak, and then falling at 12 dB/octave. Low resonance (low Q).
- 2: Resonant Low-Pass: High resonance (high Q).
- 3: Notch, Resonant Low-Pass: The frequency response begins flat, then has a deep notch, then back to flat, and then a resonant peak followed by a 12 dB/octave fall.
- 4: Notch, Notch, Resonant Low-Pass: Same as 03, but with two notches.
- 5: Peak, Notch, Resonant Low Pass: A resonant peak, followed by a notch, followed by a resonant low pass.
- 6: Resonant Low Pass, Peak, Peak: As the response of the low pass filter falls, the fall is interrupted by two peaks. The low pass resonant peak moves in the opposite direction from the additional higher frequency peaks.
- 7: Two resonant low pass filters in parallel.
- 4-Pole Filters
- 8: Resonant Four-Pole Low-Pass: Like the two-pole low pass, but after the resonant peak, the signal falls at 24 dB/octave.
- 9: Four-Pole Low Pass With Two Resonant Peaks: The resonant peaks are separated by 1.3 octaves.
- 10: Peak, Four-Pole Low-Pass. A four-pole low pass with an extra peak at a lower frequency than the resonant peak.
- 11: Four-Pole Low-Pass, Peak: A four-pole low pass with an extra peak at a higher frequency than the resonant peak.
- Single Peak
- 12: Peak: The frequency response is flat, except in the region around the peak. Moderate Q.
- 13: Peak: As above, with higher Q.
- Triple Peaks
- 14, 15: Three peaks moving together.
- 16, 17: Three peaks moving in opposing directions.
- Peaks And Notches
- 18: Peak, Notch, Peak.
- 19: Notch, Peak, Notch.
- 20: Notch, Notch: A pair of frequency response notches create a standard two-notch phaser. There is a little feedback to boost the non-notched frequencies.
- 21: Notch, Notch, Notch: A three notch phaser with some feedback.
Each one of these effects is further controlled by 3 important knobs:
- Frequency: controls the centre frequency of the filter sweep.
- Sweep range: controls both the breadth and direction of the filter sweep.
- Speed: controls the speed of either the attack and delay together or only the decay.
We can get even more out of the Source Audio Guitar Envelope Filter by plugging in a wireless “Hot Hand” motion sensor ring. This additional unit tracks the motion of our playing hand to get even more dynamic results out of the envelope filter.
This digital pedal utilizes Source Audio’s proprietary 56-bit DSP and crystal clear 24-bit converters. The pedal sounds absolutely amazing and is fully deserving of a spot on this list.
Source Audio is featured in My New Microphone’s Top 11 Best Guitar/Bass Effects Pedal Brands To Know & Use.
We can’t forget about the little green box known as the DOD 440 (link to check the price on Amazon): a wonderfully simple envelope filter.
The DOD offers up to vowel-like sounds of a funky envelope filter along with the cry of slower filter sweeps. This is all made possible with 2 knobs and a single toggle switch, make the 440 one of simplest and best envelope filter pedals at the same time.
As we already know by now, the Level knob will control the sensitivity of the envelope while the Range knob will control the range of movement of the envelope’s sweep.
Toggle the sweep upward for classic envelope quack or downward bassier results.
True bypass allows the signal to pass through uncoloured while the pedal is off.
Plain and simple, the DOD 440 is one of the best envelope filters in the world.
DOD is part of DigiTech, which is featured in My New Microphone’s Top 11 Best Guitar/Bass Effects Pedal Brands To Know & Use.
Source Audio SA143
Yet another incredible pedal from Source Audio’s Soundblox line is the Source Audio SA143 (link to check the price on Amazon) bass envelope filter.
The SA143 is the successor of the popular Soundblox BEF by Source Audio.
The pro version features 4 different modulation sources to choose from:
- Classic envelope filters (which we’re concerned with).
- Selectable LFO wave forms with tap tempo.
- Passive expression pedal.
- Hot Hand motion sensing ring.
This pedal also stores up to 6 user-defined presets. It has full MIDI compatibility.
There are 22 effects types/modes built into the SA143 (that’s 1 more than the aforementioned Source Audio SA127). Like the SA127, the effects are organized into 6 different categories:
- 2-Pole Filters (7 effects)
- 4-Pole Filters (4 effects)
- Single Peak (2 effects)
- Triple Peak (4 effects)
- Peak & Notch (2 effects)
- Phasers (3 effects)
The mode dial can also be set to “EQ Only” in order to bypass all effect besides the built-in EQ of the SA143.
As mentioned, each filter type can be modulated by 4 different methods (including envelope filtering). In addition to this, further modifications can be made via a 7-band graphic EQ.
The envelope filter can be adjusted via the following knobs. We’ve already discussed these effects so I’ll simply list them out!
- Mix (wet/dry)
- Speed (attack and decay or decay only)
- Range (wide or shallow as well as sweep direction)
- Frequency (centre frequency)
On top of that, there are even more parameters are accessible via the SA143’s special Backpage mode.
So the SA143 by Source Audio goes beyond envelope filtering. That being said, when it is set to modulate the signal via envelop filtering, it’s one of the best pedals to produce the effect!
MXR M82 Bass Envelope Filter
Surely a list like this wouldn’t be complete with an MXR pedal? The MXR M82 Bass Envelope (link to check the price on Amazon) is one of the best for getting a funky auto-wah on the bass guitar.
The MXR M82 is a great choice for bassists looking to get the best funky auto-wah sounds. The all-analog circuitry offers rich, organic tones and the pedal is designed specifically to act upon bass guitar signals.
This bass envelope filter sounds great a can keep up with passive and active bass pickups with ease. The pedal also has true bypass so it won’t colour the sound when in bypass (off) mode. Dial-in the controls to get the exact envelope filter sound you’re looking for.
As we can see above, the MXR M82 is pretty straightforward. It has a mono input and a mono output along with 5 knob controls. The controls are:
- Dry: controls the output level of the direct signal.
- FX: controls output level of envelope filter signal.
- Decay: sets envelope filter’s decay stop frequency.
- Q: controls the intensity of the effect.
- Sens: adjusts the sensitivity at which the envelope triggers.
There’s no control over sweep direction. The sweep direction of the M82 filter is always downward, which tends to sound best on bass anyway.
Adjust the Dry and FX levels to find the perfect balance between the envelope filter effect and the low-end of the dry signal.
What we get with the MXR Bass Envelope Filter is a clean and classic envelope filter sound in a small, durable unit that can be put on any pedalboard and taken on any gig!
MXR is featured in My New Microphone’s Top 11 Best Guitar/Bass Effects Pedal Brands To Know & Use.
The Electro-Harmonix Bassballs (link to check the price on Amazon) is perhaps the simplest envelope filter on the market with a single knob, toggle switch and stomp button.
The Bassballs is a very liquid, vowel-like pedal (even more so than other envelope filters). This unit utilizes two narrow filter sweeps, both controlled by the envelope, to generate this unique effect.
There’s actually only one control for the actual envelope filter circuit in this pedal and that’s the Response knob. This control varies the sweep range of both filters at once. Dial it in to your liking.
The other control is a toggle switch that sends the signal through a distortion circuit.
This super-simple pedal is a perfect companion for liquid bass envelope filtering and also sounds very funky on guitar. Its build is very durable and its small footprint makes it easy to fit on a pedalboard.
Mr. Black Fwonkbeta Purple Funk Generator
This next pedal is fun to say and even more fun to play. It’s the Mr. Black Fwonkbeta Purple Funk Generator (link to check the price at Mr. Black Pedals).
The Fwonkbeta is certainly a standout envelope filter when it comes to bringing the funk. It’s a pedal aimed at bassists to provide them with all the funkiness of a top-notch envelope filter while maintaining the thick low-end that is sometimes missed in envelope filtering circuits.
The labelling of this pedal adds to its funkiness. It’s a relatively simple build with 3 control knobs.
- Stroke: this basically controls the input sensitivity of the envelope filter.
- Fwonk: this knob controls the range of the filter sweep.
- Juice: this controls the resonant peak of the filter.
The Fwonkbeta Purple Funk Generator is one of the tightest and “stankiest” envelope filter pedals for bass guitar. It’s simple, small and sounds absolutely amazing!
Xotic Robotalk 2
The second last pedal is the the expertly-designed Xotic Robotalk 2 (link to check the price on Amazon).
The Xotic Robotalk 2 offers two individual envelope filter channels, each with its own voice. This standout feature, along with its versatility and superior sonic quality, makes the Robotalk 2 one of the best envelope filter pedals out there.
Each channel is capable of the full spectrum of funky envelope filter effects. Adjust the sensitivity, envelope decay, resonance and volume of each channel. Use them one at a time or blend the two together for novel-sounding and impressive auto-wah tones.
This true bypass pedal also features a switchable input pad to easily accommodate active and passive pickups.
The Xotic Robotalk 2 offers slow acoustic-like attack; percussive, high speed open-close, and much more. Blend each channel together for additional tone or use the internal dip switch to customize your sounds appropriately.
Mu-Tron Micro-Tron IV
To finish the list at number 13, allow me to introduce the almighty Mu-Tron Micro-Tron IV (link to check the price at Sam Ash).
Mu-Tron Micro-Tron IV is the successor to the classic Mu-Tron III envelope filter. This pedal gives us all the beloved Jerry tone and Bootsy funk achieved with the Mu-Tron III in an easily-powered, pedalboard-friendly sized unit.
With the IV model, we can adjust the output level and the sweep direction for added control.
Let’s have a look at the Micro-Tron IV’s controls:
- LP (lowpass filter): passes all the signals below the peak and attenuates signals above the peak.
- BP (bandpass filter): passes signals only near the peak and attenuates signals below and above the peak.
- HP (highpass filter): passes all signals above the peak and attenuates signals below the peak.
- LO (low): sets the filter sweep to a low range for most rhythm guitar, bass and lower fret uses.
- HI (high): sets the filter sweep to a high range for accenting string harmonics or for up-the-neck and solo work.
- Level: controls the ouput volume of the effected signal.
- Peak (Q): controls the filter audio response from very weak to very strong.
- Gain: controls the envelope and filter audio drive.
- On/Off Footswitch: engages or disengages the envelope filter effect
- Up/Down Footswitch: alters the sweep direction.
This pedal also has a CV input to accept an expression pedal for even more control over the envelope sweeping parameters. On top of that, we can send the envelope from the Micro-Tron IV to other Mu-Tron units such as the Phasor III and Bi-Phase pedals from even more funkiness!
The Mu-Tron Micro-Tron IV sounds so good and is so versatile, we can use it on any instrument we like and get amazing results. Try one out for yourself and you’ll be instantly sold.